In densely packed electronic apparatus such as portable computers ever greater heat generating components are being introduced in order to enhance performance. Where the electronic apparatus is very compact it is frequently necessary to have a portion of the apparatus container hinged which adds complexity in transporting heat generated by the apparatus from one place to another place on the opposite side of the hinge. Considering the portable computer as an illustration, the packaging has evolved into the use of a case in which in a base, a keyboard is positioned adjacent to the user, and on which, on a hinged cover, a display is positioned to be facing the user, when the cover is open. The package or case is about the size of a notebook and weighs about five pounds. The capacity and performance of portable computers have been enhanced to such an extent that the thermal dissipation requirements of such apparatus has now increased from about 10 watts to 25 watts or higher. It is becoming desirable to continue to increase the thermal dissipation capability of the apparatus.
One limitation however has been the fact that the heat pipe while it is very efficient in moving heat and does not require much space, heretofore in the art, has not responded very well to the transporting of the heat through the moveable parts of a hinge in an electronics package. In many heat dissipation structures in the art there is a first or primary heat pipe that transfers heat from a relatively locallized heat source located in the main or base portion of the apparatus package, to the hinge, and then from the hinge, there is serially connected, another or secondary heat pipe that further transfers the heat to a dissipator located in the hinged portion of the apparatus package. In the use of heat pipes, for good thermal efficiency both end regions of the heat pipe should have a fused, such as soldered, heat transfer connection, and this heretofore has not been achieved in the moveable parts of an electronic apparatus hinge.
Many developments in the art heretofore have focused on reduction of thermal resistance at the rotating interface between primary and secondary heat pipe segments by freeing an end of a heat pipe from being fused so that it can rotate and then reducing thermal resistance through use of thermally conducting grease.
In U.S. Pat. No. 5,588,483 there is shown packaging technique where heat is conveyed by a heat pipe into the center of a heat conducting grease filled pipe for transfer to a metal radiating member that has an edge attached lengthwise to the pipe.
In U.S. Pat. No. 5,313,362 there is disclosed a packaging concept which incorporates various fins and other radiation structures including fins for dissipating heat through convection and includes the ultilization of extended portions of a non standard apparatus package.
In Taiwan patent publication TW272263-A there is disclosed a packaging technique in which a clamp permits a heat pipe end to revolve in the hinge.
In U.S. Pat. No. 5,646,822 there is disclosed a packaging technique wherein two heat pipe ends enter opposite ends of a common tube and rotate within it using a thermally conductive grease for lubrication and some reduction of thermal resistance.
In a publication by Mochizuki, et al., titled "Hinged Heat Pipes for Cooling Notebook PCs", Thirteenth IEEE SEMI-THERM Symposium, 1997, there is discussed an apparatus that connects two heat pipes together serially using two clamps. The apparatus however uses dry contact and clamp force to try to reduce the thermal resistance resulting from having at least one end of a heat pipe without a fused type connection.
There is a need in the art for improvement in the ability to join serial heat pipes in a moveable hinge connector that will transmit heat through the moveable region with greater efficiency.